package com.wqz.test;

import java.util.HashMap;
import java.util.Map;

/**
 * @Date 2021/9/7 9:38
 * @Created by 吴桥志
 * @Version 1.0
 */

public class test01 {
    public static void main(String[] args) {
        int[] a = new int[2];
        System.out.println(a.length);
        //String s = new String("aaaaa");
        String s = "aaaaa";
        System.out.println(s.length());

        Map<Object, Object> map = new HashMap<>();
        map.put(null,"1");
        map.put(null,"2");
        map.put("3","4");
        System.out.println(map.get(null));
        System.out.println(map.get("3"));

    }


}

